A purple team exercise is not a red team with a friendlier name. It is a deliberate loop: execute a technique, watch what the defenders see, fix the gap, execute again.
The loop
- Pick a technique and agree what success looks like for both sides.
- Execute it, with timestamps recorded precisely.
- Check the telemetry: was the activity logged at all, did a rule fire, did an analyst notice, how long did each step take?
- Fix whatever failed — a missing log source, a rule, a threshold, a runbook.
- Re-run it the same day and confirm the fix.
Why it beats a report
A red team report arrives weeks later and lists what was missed. A purple exercise fixes the misses while the people who own the detections are in the room, and ends with evidence that the detection now works.
What to prepare
Agreed techniques, a test environment that resembles production in its logging, timestamp discipline on both sides, and an explicit list of what the blue team is told in advance. Also decide how findings are recorded — a detection gap is a backlog item, not a bullet in a slide.
How often
Little and often beats annually. A monthly half-day against three techniques produces more durable improvement than one large exercise a year, because the fixes get verified.